From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Hillf Danton <hdanton@sina.com>,
Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: johan.hedberg@gmail.com, linux-bluetooth@vger.kernel.org,
linux-kernel@vger.kernel.org, luiz.von.dentz@intel.com,
marcel@holtmann.org, netdev@vger.kernel.org,
syzkaller-bugs@googlegroups.com,
syzbot <syzbot+47c6d0efbb7fe2f7a5b8@syzkaller.appspotmail.com>
Subject: Re: [syzbot] general protection fault in hci_release_dev
Date: Mon, 2 Aug 2021 20:02:24 +0900 [thread overview]
Message-ID: <92ae9eb0-0a9c-f73a-57f3-20059d9e4c21@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20210802095403.2100-1-hdanton@sina.com>
Hello.
On 2021/08/02 18:54, Hillf Danton wrote:
> To fix what was addressed in e305509e678b3a4a, defer putting hdev until
> sock is released with sock locked.
>
> Now only for thoughts.
Thanks for your analysis.
hci_alloc_dev() is called from hci_uart_register_dev() from hci_uart_set_proto()
from hci_uart_tty_ioctl(HCIUARTSETPROTO) via ld->ops->ioctl() from tty_ioctl(),
and bt_host_release() is called from device_release() from kobject_put() from
hci_uart_tty_close() from tty_ldisc_kill() from tty_ldisc_release() from
tty_release_struct() from tty_release() from __fput().
The problem is that bt_host_release() is expecting that hci_register_dev()
was called if "struct hci_dev" was allocated by hci_alloc_dev(). In other
words, hci_register_dev() might not be called before bt_host_release().
Then, the fix I think is not to call hci_release_dev() when hci_unregister_dev()
was not called. That is,
static void bt_host_release(struct device *dev)
{
struct hci_dev *hdev = to_hci_dev(dev);
+
+ if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
+ hci_release_dev(hdev);
kfree(hdev);
module_put(THIS_MODULE);
}
and remove kfree(hdev) from hci_release_dev(), for HCI_UNREGISTER flag is
set if hci_unregister_dev() was called before bt_host_release() is called.
next prev parent reply other threads:[~2021-08-02 11:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-02 4:07 [syzbot] general protection fault in hci_release_dev syzbot
[not found] ` <20210802095403.2100-1-hdanton@sina.com>
2021-08-02 11:02 ` Tetsuo Handa [this message]
2021-08-02 11:38 ` Marcel Holtmann
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=92ae9eb0-0a9c-f73a-57f3-20059d9e4c21@i-love.sakura.ne.jp \
--to=penguin-kernel@i-love.sakura.ne.jp \
--cc=hdanton@sina.com \
--cc=johan.hedberg@gmail.com \
--cc=linux-bluetooth@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luiz.dentz@gmail.com \
--cc=luiz.von.dentz@intel.com \
--cc=marcel@holtmann.org \
--cc=netdev@vger.kernel.org \
--cc=syzbot+47c6d0efbb7fe2f7a5b8@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).